A major argument in favor of local defects in the host defense against staphylococcal foreign-body infections was obtained by studies performed with experimentally infected animals. Effective protection from foreign-body infection was indeed obtained by injection of fresh neutrophils into tissue cages. In vitro studies aiming to describe mechanisms of bacterial attachment relevant to the colonization of indwelling devices are frequently performed in the absence of any hostrelevant factors. A section of this chapter emphasizes the critical role of host proteins, whether surface-bound or in the fluid phase, in modulating staphylococcal attachment to artificial implants. More recent studies using specific adhesin-defective mutants of Staphylococcus aureus confirmed the role of fibronectin in promoting bacterial attachment to subcutaneously implanted coverslips. The high susceptibility of patients with indwelling devices to microbial infections results from important defects in the cytokine and phagocytic-bactericidal responses. Experimental models have documented these defects in the vicinity of subcutaneously implanted tissue cages locally challenged with S. aureus or S. epidermidis. Such implanted tissue cages or coverslips were found to be progressively colonized by host-derived humoral and cellular elements. A number of approaches may be considered for reducing host susceptibility to foreign-body infections. An improved understanding of molecular and physiological mechanisms of phenotypic antibiotic tolerance of implant-associated organisms might bring new clues to more effective treatment strategies.

(Left) Immunofluorescent staining of fibronectin recovered on PMMA coverslips excised from the guinea pigs after 4 weeks of subcutaneous implantation. (Reprinted from reference 128 with permission.) (Right) Adhesion of the parental strain 8325-4 of S. aureus and its knockout mutant strain DU5883 defective in the production of both fibronectin-binding proteins. (Reprinted from reference 46 with permission from Blackwell Science Ltd.)

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Figure 3.

(Left) Immunofluorescent staining of fibronectin recovered on PMMA coverslips excised from the guinea pigs after 4 weeks of subcutaneous implantation. (Reprinted from reference 128 with permission.) (Right) Adhesion of the parental strain 8325-4 of S. aureus and its knockout mutant strain DU5883 defective in the production of both fibronectin-binding proteins. (Reprinted from reference 46 with permission from Blackwell Science Ltd.)

(A) Analysis of SDS-extracted proteins from inserted cannulas by SDS-PAGE. Protein extracts from four different cannulas (lanes 2 to 5) were electrophoresed in parallel with 100 ng of purified fibrinogen (lane 1) and 1000-fold diluted plasma (lane 6) in a 5 to 15% PAGE gradient and silver stained. (B) Identification of either fibrin(ogen) or plasmin(ogen) by immunoblots with specific antibodies. Two of these protein extracts were further probed by immunoblot with antifibrinogen antibodies (lanes 2 and 3) in parallel with purified fibrinogen (lane I). The first extract (lane 2) shows mainly beta-, but not alpha- and gamma-chains, whereas the second extract (lane 3) shows both alpha-and beta-chains. Immunoblots show one additional band of 95 kDa in both extracts, representing cross-linked dimers of gamma-chains, plus a major proteolytic fragment of 40 to 43 kDa in one extract (lane 2). Immunoblots with antiplasminogen antibodies also show the presence of plasminogen in one cannula protein extract (lane 5) run in parallel with purified plasminogen (lane 4). (P. Lerch, J. J. Morgenthaler, D. Pittet, and P. E. Vaudaux, unpublished data).

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Figure 6.

(A) Analysis of SDS-extracted proteins from inserted cannulas by SDS-PAGE. Protein extracts from four different cannulas (lanes 2 to 5) were electrophoresed in parallel with 100 ng of purified fibrinogen (lane 1) and 1000-fold diluted plasma (lane 6) in a 5 to 15% PAGE gradient and silver stained. (B) Identification of either fibrin(ogen) or plasmin(ogen) by immunoblots with specific antibodies. Two of these protein extracts were further probed by immunoblot with antifibrinogen antibodies (lanes 2 and 3) in parallel with purified fibrinogen (lane I). The first extract (lane 2) shows mainly beta-, but not alpha- and gamma-chains, whereas the second extract (lane 3) shows both alpha-and beta-chains. Immunoblots show one additional band of 95 kDa in both extracts, representing cross-linked dimers of gamma-chains, plus a major proteolytic fragment of 40 to 43 kDa in one extract (lane 2). Immunoblots with antiplasminogen antibodies also show the presence of plasminogen in one cannula protein extract (lane 5) run in parallel with purified plasminogen (lane 4). (P. Lerch, J. J. Morgenthaler, D. Pittet, and P. E. Vaudaux, unpublished data).

In vitro compared with in vivo elimination (see text for details) of the methicillin-resistant strain MRGR3 of S. aureus, by either teicoplanin (Teico), vancomycin (Vanco), daptomycin (Dapto), ciprofloxacin (Cipro), fleroxacin (Flero), sparfloxacin (Sparflo), or temafloxacin (Tema). These are pooled data from four reports (8, 84, 107, 108), except those on daptomycin which are unpublished. (Reprinted from reference 120 with permission.)

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Figure 7.

In vitro compared with in vivo elimination (see text for details) of the methicillin-resistant strain MRGR3 of S. aureus, by either teicoplanin (Teico), vancomycin (Vanco), daptomycin (Dapto), ciprofloxacin (Cipro), fleroxacin (Flero), sparfloxacin (Sparflo), or temafloxacin (Tema). These are pooled data from four reports (8, 84, 107, 108), except those on daptomycin which are unpublished. (Reprinted from reference 120 with permission.)

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